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New Process Takes Energy From Coal Without Burning It
rtoz writes "Ohio State students have come up with a scaled-down version of a power plant combustion system with a unique experimental design--one that chemically converts coal to heat while capturing 99 percent of the carbon dioxide produced in the reaction. Typical coal-fired power plants burn coal to heat water to make steam, which turns the turbines that produce electricity. In chemical looping, the coal isn't burned with fire, but instead chemically combusted in a sealed chamber so that it doesn't pollute the air. This new technology, called coal-direct chemical looping, was pioneered by Liang-Shih Fan, professor of chemical and biomolecular engineering and director of Ohio State's Clean Coal Research Laboratory."
Sounds nice, except for the 'combusted in a sealed chamber' bit. How is this going to scale up so they can feed 100 tons/hr through the plant cycle? That is the question.
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How does the lack of pollution from the process compare against that generated from the acquisition of the coal?
Is it possible/practical to convert an existing coal power plant?
Is there an appreciable energy/pollution cost to produce the fine powder coal used in the process?
How much energy is consumed or how much pollution is produced in transporting the coal to the reactor?
Is the process itself efficient in regards to the energy output when compared against the total energy costs?
I'm sure there's a lot of other things that don't spring to mind instantly, but I'm certainly not an expert on any of this. Doubts notwithstanding, this is pretty cool.
Its not emission-less. If you read his presentation from 2008 you'll see that the C02 is the byproduct of the reaction that is is used to transfer heat to the steam boiler. The C02 still gets generated as before, just now it can be more readily sequestered - assuming that you want to spend the money on that part of the equation.
Coal Direct Chemical Looping Retrofit for Pulverized Coal-fired Power Plants with In-Situ CO2 Capture (PDF - but why the hell in this day and age do I need t tell you that? Can't you just look at the link?)
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There is no burning. Apparently that is the key innovation. The chemical reaction between the coal dust and the rust pellets releases the CO2 in a very controlled manner with the CO2 being separated cleanly rather than mixed up with smoke aka carbon molecules. That must make the CO2 capture much much easier.
A fool throws a stone into a well and a thousand sages can not remove it.
We already burn a crap load of coal for our electricity. Wouldn't it be great if we worked to make it clean-er ( at least in terms of soot and mercury released into the air)? There isn't much on the horizon that could replace coal over night. We should try to find something will all due haste, but it wouldn't hurt to get the low hanging fruit. Its pretty much what Obama is doing now and its a sensible approach.
Well.. maybe. Or Maybe not. But Definitely not sort of.
A better word might have been "oxidized" but the good professor probably was trying not to confuse the journalism major
who wrote the story with words too big for their tiny world view.
Lots of CO2 is produced, but it is retained in the chamber and captured, and oxygen and coal are fed in continuously.
They operated it for 9 days straight.
Sig Battery depleted. Reverting to safe mode.
The researchers are about to take their technology to the next level: a larger-scale pilot plant is under construction at the U.S. Department of Energy's National Carbon Capture Center in Wilsonville, AL. Set to begin operations in late 2013, that plant will produce 250 thermal kilowatts using syngas.
From 25 kw to 250kw
Sounds like they're scaling it up.
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o0t!
Why not just burn coal and air in an oven and capture the CO2
Because only part of the air gets converted to CO2. Most of the air is nitrogen, and only ~21% is oxygen. Even if you have complete conversion of the oxygen to CO2 (not going to happen), you'd end up with exhaust gas that's mostly nitrogen with some carbon dioxide mixed in. This nitrogen/carbon dioxide mix is difficult to deal with. To do anything with the CO2 you'd have to separate it from the nitrogen and residual oxygen, which gets complicated and expensive.
The hard part is surely the CO2 capture, not the burning.
Exactly. This new method attempts solve that by separating the CO2 generation stage from the air-using stage. If you could effectively separate them, you'll get a pure CO2 stream in one half of the reactor (which if you can keep closed you can pump off into storage tanks) and you'll keep the nitrogen/depleted-oxygen mix in the other half of the reactor, away from your pure CO2.
The way it works is to use iron oxide as an oxygen shuttle. The iron oxide pellets grab oxygen from the air half of the reactor, and are then transferred as a relatively gas-free solid to the coal half of the reactor, where they give up their oxygen to produce a relatively pure stream of CO2. The pellets are then separated from the coal ash and transferred as a relatively gas-free solid back to the air half of the reactor, where they are recharged with oxygen. If you engineer it right, you could conceivably make it a continuous feed operation, where you shuttle the iron oxide beads back and forth through airlocks, keeping most of the CO2 in the sealed reactor where it can be pumped off as a comparatively pure gas.
It's 2.5% less efficient than a normal coat power station.
Normal plant: 36.43%
This thing: 33.93%
It actually produces 10% more power from the turbine, but the supporting pumps, fans and compressors need to be powered.
Coal isn't clean though. This would clean up the side of the equation where you're burning it. But, it would do absolutely nothing for the mining aspect of it. Which is a huge mess as it stands. If you want to burn things for energy, you're better off starting with something like trees which are mostly carbon neutral as it is.
Sure, it's technically clean if you ignore the incredible damage that it reeks on the landscape, but it's definitely not clean in a practical sense.
Coal is oxidized to produce CO2 and heat. That's "burning", regardless of whether you use air or iron oxides as the oxidizer.
Ummm, sorry, I'm gonna have to go with the Ph.D. in Chemistry on this one buddy, and he says it's NOT burning. I would not call your comment, Informative. Uninformed, but not informative. Ooo, that's a t-shirt right there...
From TFA:
No other lab has continuously operated a coal-direct chemical looping unit as long as the Ohio State lab did last September. But as doctoral student Elena Chung explained, the experiment could have continued.
“We voluntarily chose to stop the unit. We actually could have run longer, but honestly, it was a mutual decision by Dr. Fan and the students. It was a long and tiring week where we all shared shifts,” she said.
Fan agreed that the nine-day experiment was a success. “In the two years we’ve been running the sub-pilot plants, our CDCL and SCL units have achieved a combined 830 operating hours, which clearly demonstrates the reliability and operability of our design,” he said.
His entire staff of grad students manned the thing and kept feeding it coal for a week and it ran nonstop the whole time, and could have kept going. So this appears to be a solved problem.
Weaselmancer
rediculous.
I emailed the authors after I wrote that and they emailed me back quickly. They said the only NOx comes from the Nitrogen in the Coal. None is produced in the combustion of Iron.
This would significantly lower the scrubbing requirements and cost.
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Actually capturing is the key. A carbon capturing plant is always going to be less efficient than a non-capturing plant. Try looking at it this way:
36.43% Non-capturing plant
29.14% Post-combustion capturing plant (36.43/1.25)
33.93% This thing
For a fuel that requires little or no processing it's extremely energy dense. Ultimately the problem wouldn't be with the process but the budget minded power companies. There's a reason "clean coal" is like bigfoot, largely a myth. Clean coal would cost more money reducing profits. It's the reason the industry doesn't remove mercury and coal dust from the exhaust, reduced profits. They even had a government mandate and the still waited until the deadline and are now saying it's too hard. The process can trap 99% of the CO2, the trick is keeping the power companies from not releasing it into the atmosphere to save money. White Diesel is a great source of fuel and second only to natural gas for being a clean fossil fuel but it involves stripping of the CO2 and you are faced with the same problem. Sequestration isn't as simple as it sounds. Compressing huge amounts of CO2 gas takes energy and the underground storage areas don't tend to be near power plants. When you start burning more coal just to store the CO2 from the last batch the efficiency goes way down. If the existing plants had been positioned and built with all this in mind we wouldn't have all these problems. Now there are no cheap and easy solutions. Personally I prefer using algae or greenhouses to store the CO2. Try this approach, pump the CO2 into large cheap greenhouses that grow Kenaf, it's related to hemp but totally legal and interchangeable with industrial hemp. Use as much as industry needs for fiber and seed oil then turn the rest into biochar, a good one to read up on if you aren't familiar. The char can be mixed with farmland improving the soil and it'll absorb the excess fertilizer reducing run off and reducing the amount needed to grow food. The carbon is stored for thousands of years, if not millions. The power companies get to make extra money off the Kenaf and they greatly reduce the CO2 and mercury released. The Mercury will get trapped in the char and the CO2 will be stored as solid carbon. These days they try to solve everything with technology when mother nature has been doing it for billions of years.